Crab grass is unsightly and extraordinarily difficult to remove once it has taken hold in your lawn. The only way to remove crab grass from your lawn without risking damage to the desirable grass is to pull it from the lawn by hand. However, if you have a large lawn or a lot of crab grass, removing it by hand is not likely to be your first choice for how to spend your Saturday. Another good choice is a commercial crab grass killer that uses a method designed to reduce damage to your lawn.
Cut a six-inch piece from a three- to four-inch diameter PVC pipe, or roll a piece of sturdy cardboard into a large tube.
Mix a commercial crab grass killer in a tank sprayer with the required amount of water. Refer to the manufacturer's instructions for the appropriate proportion of chemical to water.
Place the PVC pipe or cardboard tube over the crab grass and spray the weed killer down the tube. Repeat this process for every tuft of crab grass in your lawn.